Behaviors of Axial and Radial Electromagnetic Force for Cryogenic Disk Motor

There are axial and radial electromagnetic forces between the stator and rotor of axial flux disk motor besides the useful torque. The electromagnetic forces act on the rotor and are crucial to the stable operation in magnetic levitation applications driven by disk motor. This article concerns the behaviors of axial and radial electromagnetic forces of disk motor using for cryogenic submersible pump. It is measured experimentally that the electromagnetic properties of motor materials, including the electrical conductor and magnetic conductor materials, in room temperature (RT) and liquid nitrogen (LN
₂
) environment. Then, the 3D finite element model (FEM) of the three-phase asynchronous disk motor in RT environment is built which is also validated by the RT experimental tests. Finally, the behaviors of axial and radial electromagnetic forces in LN
₂
environment are investigated using the modified FEM taking account of the effect of cryogenic environment on the motor material. It is concluded that the axial electromagnetic force decreases monotonously with the increasing air-gap thickness or the decreasing rotating speed. When the rotor exhibits radial eccentricity, there is a restoring radial electromagnetic force, trying to pull the rotor back to the central position. The radial electromagnetic force increases with the increasing rotational speed and radial eccentric displacement.